1. Field of the Invention
The present invention is directed to a fermentation system involving extraction of components from solid particles into a liquid. In particular, the present invention relates to a wine fermentation device for periodically turning the cap or skins, seeds and stems which during fermentation form the cap, and for removing the skins, seeds, part of the pulp and stems which form the pomace from the tank after fermentation has been completed.
2. Prior Art
In the process of wine making, grapes are converted into wine in a fermentation vat or tank. The various processes may be varied somewhat both in the particular steps, the quantities involved, and in the durations. Wine may be fermented in small quantities of a few gallons at home up to large quantities in tanks holding thousands of gallons. Modern wineries use stainless steel tanks that can hold up to 150,000 gallons. The tanks may be jacketed to control the liquid temperature. This is accomplished in a number of known ways, such as circulating a liquid, such as glycol, through the jackets.
In a typical process, the grapes are picked in clusters and initially cleaned of foreign matter. The stems may or may not be removed but oftentimes at least part of the stems are left on. The grapes are crushed and the xe2x80x9cmustxe2x80x9d or entire unfermented crushed grape mass sometimes including the stems is put in the fermentation vat. The must is inoculated with yeast to begin fermentation. The evolution of the carbon dioxide causes the skins to rise to the surface of the wine and form a dense cap. Ordinarily, the seeds and stems sink to the bottom of the tank but some are lifted with the buoyant skins. The skin of the grapes, some of the seeds, and some stems form a cap which is buoyant and typically will float to the surface of the wine (or at that time, juice or fermenting must) mixture after inoculation.
The grape skins, seeds and stems is called a cap during the fermentation process. The mass of grape skins, seeds and stems left after fermentation is complete is called pomace.
A number of factors will be measured and adjusted during the wine making process. The sugar content is measured as the alcohol will be dependent thereon. Titratable acidity is the measure of the total acid in the grape juice. The pH will also be measured.
Thereafter, yeast is added to the mixture or must. Once the fermentation begins, the cap must be periodically mixed with the liquid mixture, punched down or pumped over. Extraction of the requisite amount of red color from the skins will not be obtained unless there is contact between fluid and the cap. For example, it may be desirable to punch the cap down twice a day. In smaller batches, this can be done by hand. In larger tanks, a rake or other instrument is used for punching down. A pump is used in a pump over to draw off fermenting fluid below the cap and distributed over the cap.
After fermentation, the wine is drained and stored in containers and the solids (or pomace) which consists of skins, seeds, part of the pulp and, perhaps, stems must be removed. In the past, it was necessary for personnel to enter the tank and rake or shovel the pomace out.
Accordingly, there remains a need for a fermentation vat that will be capable of periodically rolling, submerging or wetting the cap as desired to assist in the fermentation and making of the wine.
There is also a need for a fermentation system to remove pomace from the fermentation vat without human intervention.
There is a further need to provide a fermentation system to control and optimize the color, tannin and bitterness extraction during the wine making process.
There is an additional need to provide a fermentation system which will enhance repeatable wine processing and repeatable validation.
The present invention is directed to a wine fermentation device and a process to ferment wine.
The device includes a tank having cylindrical walls, an axis therefore, and a bottom. An optional top on the tank forms a closed vessel. Must or grape juice, crushed grapes, skins, seeds and stems are loaded into the tank at the beginning of the wine fermenting process.
The tank includes a plurality of interior baffles which extend from the cylindrical tank walls inward toward the axis.
A pair of impellers are provided within the tank. Each impeller has a plurality of extending blades which serve to radially and axially move the cap in the tank during fermentation. The impellers also serve to blend the cap with liquid in order to permit draining of the cap through a drain which is provided in the cylindrical walls at or near the tank bottom. The first impeller is axially spaced from the second impeller which is located near the bottom of the tank.
In a present, preferred embodiment, each impeller has three radially extending blades. Each blade has approximately 45xc2x0 pitch or varying pitch. The pitch on the blades forces the liquid to move radially and also to move axially as well. The impellers are each connected to a shaft. The shaft is axially aligned with the axis of the tank. The shaft extends through the top and/or bottom of the tank and is connected to a motor. The motor 20 will rotate the shaft and, accordingly, drive the impellers.
The tank bottom is sloped toward the drain or drains located near the base of the bottom. Accordingly, draining of the tank is facilitated. The cap, consisting of the skins, some of the seeds and some of the stems is buoyant with respect to the juice or wine and will float to the top. Rotating of the impellers will cause the juice or wine and the cap to rotate radially and also to move axially. The cap will be mixed with the underlying juice or wine. This process is known as turning the cap.
The cap, as well as the juice or wine flow, will be directed by the baffle or baffles further encouraging axial movement.
Once the fermentation process has been completed in the fermentation device, the majority of the wine will be drained from the tank. Since the drain is near the bottom of the tank, none of the cap is drained or removed at this point. Once the majority of the wine has been removed, the remaining cap and remaining wine is blended and agitated to create a slurry.
Thereafter, the slurry is drained off through the drain near the bottom. With use of the present invention, it would not be necessary for personnel to enter the tank to clean the pomace out once the fermentation process has been performed.